Process for obtaining transparent effects on regenerated cellulose fibers



Patented May 2, i950 PROCESS FOR OBTAINING TRANSPARENT EFFECTS ON REGENERATED CELLULOSE FIBERS Paul Walter Steinlin, Basel, Switzerland, assignor to Aktiengescllschaft Cilander, Herisau, Switzerland No Drawing. Application July 31, 1946, Serial No. 687,509. In Switzerland April 22, 1943 Claims. 1

The present application is in the nature of a continuation in part of my earlier copending application Serial No. 533,788, filed May 2, 1944, now abandoned.

Transparent fabrics, also known as organdies, have as a rule been made from pure cotton materials, in particular muslin, or, more rarely, voile or other fine fabrics, such as cambric, etc. Organdies of especially fine quality were made of natural silk.

The process hereafter described relates to the production of plain or patterned, smooth or crepe transparent fabrics from materials consisting of staple fibre made from regenerated cellulose alone or of staple fibre and cotton, or of mixed cotton and staple fibre.

Various experiments were made in the past to transform textiles of this kind by the ordinary methods used for cotton fabrics. However, even by varying and adapting working conditions, such as concentration of acids and alkaline swelling agents, and the duration of the procedure, it proved impossible to turn out marketable goods. Indeed the materials hitherto produced were horny, brittle and stiffened, and in no way suited for practical use. The present process, on the contrary, produces transparent fabrics which perfectly satisfy all requirements as to appearance, lustre, softness and durability, and show a high degree of transparency combined with a remarkable clearness of weave.

These effects are obtained by subjecting the fabric, eventually after preparatory or supplementary treatment with alkaline or acid swelling agents, first to a treatment with strong, hot alkali and afterwards with strong, preferably cold sulphuric acid.

The process is suited for fabrics made of pure staple fibre made from regenerated cellulose, or woven with cotton and staple fibre made from regenerated cellulose, and also for those woven with mixed staple fibre-cotton yarn. Naturally, materials in which any or all of the above combinations are present, either in plain or pattern weave, including of course applications with embroidery or Swiss dotted weave, can also be treated by my process.

It is advantageous to delubricate and bleach the fabric to be processed. Crude fabrics can, however, be treated in the same way. In this connection it should be borne in mind that, according to the invention, this processing is suitable for use in any phase of pre-treatment.

My process can be used to advantage in combination with treatment by swelling agents. The

2 order and manner in which these treatments are applied depend on the result desired.

Treatment with strong sulphuric acid consists in applying sulphuric acid of 40-52 B. at temperatures ranging from -5 to C. for at least 5 seconds. By hot alkali is understood a treatment according to the present process with hot alkali solution of mercerizing strength, at a temperature of C. or over, having a duration of 5 seconds or more.

It is best to rinse and neutralize between acid and alkaline treatments. Drying is also advantageous. In some cases it is recommended to repeat the process wholly or in part, or even to apply it several times;

Patterned as well as plain transparent fabrics can be obtained with the present process by applying suitable reserves before the swelling treatment. For example imago effects can be achieved 20 by printing with pigments, resulting in opaque non-transparent patterns. By this method it is possible, according to the type of process chosen, to use pigment carriers proof against acid and alkaline swelling agents, such as gums or artificial resins, which result in local opaque effects, or non-acidproof thickening agents which produce stiffened transparent designs in which the effect of contrast is due to the pigmentation alone. It is moreover possible to introduce reserves during any phase of the transforming process so as to achieve, for example, a transparent effect and then, by rinsing and subsequent swelling and shrinking, obtain the appearance of crepe. It is also possible to get intermediary effects by the imprint of swelling agents and subsequent treatment with hot alkali. The reserves can even be applied during various phases of the process in such a way that the transformed material shows untreated and swollen, that is shrunken and transparent areas one next to the other.

It is evident that by printing in colours or by the use of coloured reserves such effects can be obtained in various tints.

Fabrics submitted to the present process can be dyed either before or after treatment. In this way, according to the method of procedure, the most varied results can be obtained, such as plain transparent, or, according to the different affinity for the dye caused by different local treatment, shaded effects.

My process may be illustrated by means of a single example:

A fabric made from staple fibre made from regenerated cellulose is singed, bleached and tentered. This is followed by a treatment with NaOI-I of 30 B. at 60 C. for 12 seconds. The fabric is then neutralized, rinsed and dried and subjected to the action of sulphuric acid of 465 B. at 9 C. for 9 seconds, and again neutralized and rinsed. The result is a fine transparent fabric.

I claim:

1. A multiple-step process for obtaining transparent effects on a fabric consisting predominantly of regenerated cellulose staple fibers comprising treating said fabric with hot caustic soda of mercerizing strength at temperatures of the order of 60 C. for a period of time of the order of to 12 seconds, and then treating said fabric with sulfuric acid of 40 to 52 Baum at a temperature ranging from 5 to 20 C. for a period of time of the order of 5 to 9 seconds.

2. A multiple-step process for obtaining transparent effects on a fabric consisting predominantly of regenerated cellulose staple fibers comprising treating said fabric with hot caustic soda of mercerizing strength at temperatures of the order of 60 C. for a period of time of the order of 5.

to 12 seconds, removing free caustic soda, and then treating said fabric with sulfuric acid of 10 to 52 Baum at a temperature ranging from 5 to C. for a period of time of the order of 5 to 9 seconds.

3. A multiple-step process for obtaining transparent effects on a fabric consisting predominant- 1y of regenerated cellulose staple fibers comprising treating said fabric with hot caustic soda of mercerizing strength at temperatures of the order of 60 C. for a period of time of the order of 5 to 12 seconds, rinsing and drying said fabric, and then treating said fabric with sulfuric acid of 40 to 52 Baum at a temperature ranging from 5 to 20 C. for a period of time of the order of 5 to 9 seconds.

4. A multiple-step process for obtaining transparent effects on a fabric consisting predominant- 1y of regenerated cellulose staple fibers comprising treating said fabric with caustic soda of the order of 30 Baum at a temperature of the order of 60 C. for a period of time of the order of 5 to 12 seconds, neutralizing free caustic soda, and rinsing the fabric, and then treating said fabric with sulfuric acid of to 52 Baum at a temperature ranging from 5 to 20 C. for a period of time of the order of 5 to 9 seconds.

5. A multiple-step process for obtaining transparent effects on a fabric consisting predominantly of regenerated cellulose staple fibers comprising treating said fabric with caustic soda, of the order of 30 Baum at a temperature of the order of C. for a period of time of the order of 12 seconds, neutralizing free caustic soda, rinsing and drying the fabric, and then subjecting said fabric to sulfuric acid of the order of 465 Baum at a temperature of the order of 9 C. for a period of time of the order of 9 seconds.

PAUL WALTER STEINLIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,439,517 Heberlein Dec. 19, 1922' 1,922,308 Lilienfeld Aug. 15, 1933 1,989,100 Lilienfeld Jan. 29, 1935 1,998,576 Heberlein Apr. 23, 1935 2,203,200 Haller et a1 May 28, 1940 FOREIGN PATENTS Number Country Date 323,175 Great Britain Jan. 2, 1930 

1. A MULTIPLE-STEP PROCESS FOR OBTAINING TRANSPARENT EFFECTS ON A FABRIC CONSISTING PREDOMINANTLY OF REGENERATED CELLULOSE STAPLE FIBERS COMPRISING TREATING SAID FABRIC WITH HOT CAUSTIC SODA OF MERCERIZING STENGTH AT TEMPERATURES OF THE ORDER OF 60*C. FOR A PERIOD OF TIME OF THE ORDER OF 5 TO 12 SECONDS, AND THEN TREATING SAID FABRIC WITH SULFURIC ACID OF 40 TO 52* BAUME AT A TEMPERATURE RANGING FROM -5 TO 20*C. FOR A PERIOD OF TIME OF THE ORDER OF 5 TO 9 SECONDS. 